Circuit protection method based on DC bus capacitor and vehicle controller control system

Abstract

The present invention discloses a circuit protection method based on a DC bus capacitor and a vehicle-mounted controller control system, wherein a diode is connected between a power filter and a positive electrode or a negative electrode of a DC bus capacitor, and a switch tube driven by an MCU is reversely connected in parallel between the positive and negative electrodes of the diode; wherein when the motor is not working, the switch tube is in a closed state; when the motor is working, when the voltage of the DC bus capacitor does not exceed a preset threshold value, the switch tube is in a closed state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold value, the switch tube is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply; the present invention reliably avoids the occurrence of the resonance problem, and at the same time ensures the service life and reliability of the circuit of the present application through a simple, reliable and low-cost solution.

Description

Technical Field

[0001] The present invention belongs to the field of vehicle-mounted compressor control, and specifically relates to a circuit protection method based on a DC bus capacitor. The present invention also relates to a vehicle-mounted controller control system to which the circuit protection method is applied. Background Art

[0002] In the field of vehicle compressor control, under normal circumstances, the high voltage side is powered by the vehicle battery, and the input voltage is usually DC350V, so that the vehicle controller control system can work stably. Figure 1 As shown, sometimes the high-voltage side input voltage a (i.e., the DC bus voltage) will be superimposed on the AC quantity to form a high-voltage side input voltage a'. The main reason for this is that other loads on the vehicle will disturb the output voltage of the battery.

[0003] In order to solve the above technical problems, the existing technology proposes to use a bus capacitor with very small capacity, so that the resonant frequency point of the control circuit is far away from the frequency required by the standard. The standard requires a frequency range of: 100-100KHz; and because the capacitor is a high-voltage ceramic capacitor, it has good high-frequency performance and strong ripple resistance, and is not easily damaged when used in this occasion. However, the applicant found that the small capacitance used in this solution leads to large bus voltage ripple, which in turn limits the output capacity of the compressor, making it difficult to increase the load capacity of the compressor, and the scope of application is greatly restricted, which cannot meet the needs of actual applications.

[0004] Therefore, based on the inventors' many years of dedicated research and development experience in the control field, they hope to seek innovative solutions to solve the above technical problems. Summary of the invention

[0005] In view of this, the purpose of the present invention is to propose a circuit protection method based on DC bus capacitor and a vehicle-mounted controller control system, which can reliably avoid the occurrence of resonance problems, and at the same time ensure the service life and reliability of the circuit of the present application through a simple, reliable and low-cost solution.

[0006] In the control circuit of the vehicle controller, the EMI filter is mainly an inductive element. The circuit composed of the inductive element and the DC bus capacitor will form the inherent oscillation frequency of the control circuit (i.e., generate an oscillation loop). When the input voltage is superimposed with the AC signal and is close to the inherent oscillation frequency of the control circuit, it will cause resonance between the control circuit and the input signal; this resonance will cause the oscillation amplitude of the oscillation signal to gradually increase, which will have a serious destructive effect on the control circuit, especially causing the DC bus capacitor in the circuit to heat up and be damaged in a very short time.

[0007] To this end, the technical solution adopted in the present invention is as follows:

[0008] A circuit protection method based on a DC bus capacitor, the circuit includes a DC bus capacitor connected to a motor drive module, an MCU is connected to a motor drive through the motor drive module, and the DC bus capacitor is connected to a DC power supply through a power filter; a diode is connected between the power filter and the positive or negative electrode of the DC bus capacitor, and a switch tube driven by the MCU is reversely connected in parallel between the positive and negative electrodes of the diode; wherein,

[0009] When the motor is not working, the switch tube is in the off state;

[0010] When the motor is working, when the voltage of the DC bus capacitor does not exceed the preset threshold, the switch tube is in a closed state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold, the switch tube is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply.

[0011] Preferably, the motor driving module is turned off while the switch tube is turned on.

[0012] Preferably, after the interval time of opening the switch tube, ensure that the voltage of the DC bus capacitor does not exceed a preset threshold, and close the switch tube; the MCU selects to send a drive signal to the motor drive module according to the motor operation requirements.

[0013] Preferably, the interval time is 0.00001-2.5 seconds.

[0014] Preferably, the preset threshold is greater than the rated voltage of the DC power supply and less than the withstand voltage of the DC bus capacitor and the motor drive module.

[0015] Preferably, the MCU is connected to the DC bus through a voltage sampling circuit, which is used to detect the voltage of the DC bus capacitor in real time, and compare the voltage of the DC bus capacitor with a preset threshold value, and selectively send a switch tube drive signal to the switch tube based on the comparison and judgment result.

[0016] Preferably, the positive electrode of the diode is connected to the power filter, and the negative electrode of the diode is connected to the positive electrode of the DC bus capacitor; or the negative electrode of the diode is connected to the power filter, and the positive electrode of the diode is connected to the negative electrode of the DC bus capacitor.

[0017] Preferably, the capacity of the DC bus capacitor is 2-100uF; and the motor drive module includes an IPM module.

[0018] Preferably, a vehicle-mounted controller control system includes a circuit based on a DC bus capacitor, wherein the circuit includes a DC bus capacitor connected to a motor drive module, the MCU is connected to the motor drive through the motor drive module, and the DC bus capacitor is connected to the DC power supply through a power supply filter; the circuit adopts the circuit protection method as described above.

[0019] Preferably, the vehicle-mounted controller control system includes a high-voltage side power supply and a low-voltage side power supply which are electrically connected to the motor drive module respectively, and the high-voltage side power supply adopts the DC power supply; wherein, the voltage of the high-voltage side power supply is not lower than 100V, and the voltage of the low-voltage side power supply is not higher than 50V.

[0020] The present application connects a diode between the power filter and the positive or negative electrode of the DC bus capacitor. After adding the diode, it can be ensured that the electric field energy stored in the DC bus capacitor can no longer be released to the inductor element in the power filter, thereby cutting off the oscillation loop generated between the DC bus capacitor and the power filter, and finally reliably avoiding the occurrence of the resonance problem; considering that the motor is an inductive load, energy feedback may sometimes be generated. When the energy rushes to the bus, the bus voltage will increase and burn the DC bus capacitor or the bus device in the motor drive module. Therefore, the present application simultaneously reversely connects a switch tube driven by the MCU between the positive and negative poles of the diode in parallel. In actual operation, when the motor is not working, the switch tube is in a closed state; when the motor is working, when the voltage of the DC bus capacitor does not exceed the preset threshold, the switch tube is in a closed state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold, the switch tube is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply, thereby effectively protecting various devices connected to the bus, and ensuring the service life and reliability of the circuit of the present application through a simple, reliable and low-cost solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a signal diagram of the input voltage a in the background technology of the present application, and the input voltage a superimposed with the AC signal to become the input voltage a';

[0022] Figure 2 is a schematic diagram of the circuit structure in Example 1 of the present application;

[0023] Figure 3 This is a schematic diagram of the circuit structure in Example 2 of the present application.

[0024] Figure 4 is a control timing diagram of the circuit protection method adopted in Example 3 of the present application;

[0025] Figure 5 It is a structural diagram of the vehicle controller control system in Example 3 of the present application (based on the circuit structure in Example 1). DETAILED DESCRIPTION

[0026] The embodiment of the present invention discloses a circuit protection method based on a DC bus capacitor. The circuit includes a DC bus capacitor connected to a motor drive module, an MCU connected to a motor drive through the motor drive module, and the DC bus capacitor connected to a DC power supply through a power filter; a diode is connected between the power filter and the positive or negative electrode of the DC bus capacitor, and a switch tube driven by the MCU is reversely connected in parallel between the positive and negative electrodes of the diode; when the motor is not working, the switch tube is in a closed state; when the motor is working, when the voltage of the DC bus capacitor does not exceed a preset threshold value, the switch tube is in a closed state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold value, the switch tube is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply.

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Example 1: Please see Figure 2 As shown, this embodiment proposes a protection circuit based on a DC bus capacitor. The DC bus capacitor 11 is connected to a DC power supply 13 through a power filter 12. In order to avoid an oscillation loop between the DC bus capacitor 11 and the power filter 12, a diode 14 for cutting off the oscillation loop is connected between the power filter 12 and the positive or negative electrode of the DC bus capacitor 11 to avoid resonance problems. Preferably, in this embodiment, the cathode of the diode 14 is connected to the power filter 12, and the anode of the diode 14 is connected to the cathode of the DC bus capacitor 11.

[0029] Further preferably, in this embodiment, a switch tube driven by MCU1 (abbreviation of Microcontroller Unit) is connected in reverse parallel between the positive and negative electrodes of the diode 14; specifically preferably, in order to facilitate installation layout, in this embodiment, the diode 14 and the switch tube are integrated and packaged as one;

[0030] Preferably, in this embodiment, the power filter 12 adopts an EMI (abbreviation of Electric Magnetic Interference) power filter, and any known power filter can be used. Specifically preferably, in this embodiment, the EMI power filter includes a common mode inductor and a differential mode inductor;

[0031] Preferably, in the present embodiment, the switch tube adopts any one of IGBT15 (abbreviation of Insulated Gate Bipolar Transistor), MOS (abbreviation of MOSFET) tube and NPN triode; specifically preferably, in the present embodiment, the switch tube adopts IGBT15, and IGBT15 and diode 14 are integrated and packaged as one; wherein the gate of IGBT15 is connected to the drive signal of MCU1, its collector is connected to the cathode of diode 14, and its emitter is connected to the anode of diode 14; MCU1 is connected to IGBT15 through IGBT drive circuit 2a (any known structure can be adopted); MCU1 is connected to DC bus through voltage sampling circuit 2b, which can be combined with reference to Figure 5 The +HV_Detect signal input shown is used to detect the voltage of the DC bus capacitor 11 in real time;

[0032] Preferably, in this embodiment, an IPM (Intelligent Power Module) module 4 for driving the motor 3 is connected between the positive and negative poles of the DC bus capacitor 11, and the MCU1 sends a driving signal to the IPM module 4, wherein the IPM module 4 serves as a driving module for the motor 3 and is a bus device connected to the bus.

[0033] Embodiment 2: The remaining technical solutions of this embodiment 2 are the same as those of embodiment 1, except that, see Figure 3 As shown, in this embodiment 2, the positive electrode of the diode 14 is connected to the power filter 12, and the negative electrode of the diode 14 is connected to the positive electrode of the DC bus capacitor 11; the gate of the IGBT 15 is connected to the drive signal of the MCU 1, its collector is connected to the negative electrode of the diode 14, and its emitter is connected to the positive electrode of the diode 14.

[0034] Example 3: Please refer to Figure 4 Combined with Figure 5 As shown, this embodiment 3 further proposes a circuit protection method for the protection circuit based on the DC bus capacitor 11 in embodiment 1 or embodiment 2, and the circuit protection method includes: when the motor 3 is not working, the IGBT 15 is in a closed state; when the motor 3 is working, when the voltage of the DC bus capacitor 11 does not exceed the preset threshold, the IGBT 15 is in a closed state; when it is found that the voltage of the DC bus capacitor 11 exceeds the preset threshold, the MCU 1 turns on the IGBT 15 through the IGBT drive circuit 2a, and releases the electric field energy stored in the DC bus capacitor 11 to the DC power supply 13; in order to protect the IPM module 4 in time, preferably, the IPM module 4 is turned off while the IGBT 15 is turned on;

[0035] Preferably, in order to facilitate the normal operation of the motor 3, in this embodiment, after the interval time of turning on the IGBT 15, ensure that the voltage of the DC bus capacitor 11 does not exceed the preset threshold value, and turn off the IGBT 15; MCU1 selects to send a drive signal to the IPM module 4 according to the operation requirements of the motor 3; wherein preferably, in order to achieve effective protection of each bus device connected to the bus, in this embodiment, the preset threshold value is greater than the rated voltage of the DC power supply 13, and less than the withstand voltage of the DC bus capacitor 11 and the IPM module 4; further preferably, the MCU1 is connected to the DC bus through the voltage sampling circuit 2b, which is used to detect the voltage of the DC bus capacitor 11 in real time, and compare and judge the voltage of the DC bus capacitor 11 with the preset threshold value, and selectively send the IGBT drive signal to the IGBT 15 based on the comparison and judgment result;

[0036] In the specific implementation of the present application, a suitable interval time can be selected on the basis of ensuring that the voltage of the DC bus capacitor 11 does not exceed the preset threshold value, and the present embodiment does not impose the sole limitation on this; specifically preferably, in the present embodiment, the interval time is 0.00001-2.5 seconds, more preferably 0.0001-1 second, further preferably 0.0001-0.5 seconds, and further more preferably 0.0001-0.3 seconds, which is more conducive to the accuracy of the protection process.

[0037] In this embodiment, a diode 14 is provided between the power filter 12 and the DC bus capacitor 11, and an IGBT 15 driven by the MCU1 is reversely connected in parallel between the positive and negative poles of the diode 14. While ensuring effective protection of the DC bus capacitor 11 in the circuit, the capacity of the DC bus capacitor 11 does not need to be particularly limited and can be specifically selected according to actual application requirements, with a wide range of applications. Preferably, in this embodiment, the capacity of the DC bus capacitor 11 is 2-100uF, and more preferably 2-50uF.

[0038] Please see further Figure 5 As shown, this embodiment also proposes a vehicle-mounted controller control system 10, including a circuit based on a DC bus capacitor 11, the circuit includes a DC bus capacitor 11 connected to an IPM module 4, an MCU1 is connected to a motor 3 (belonging to a vehicle-mounted compressor motor) through the IPM module 4, and the DC bus capacitor 11 is connected to a DC power supply 13 through an EMI power filter 12; the circuit adopts the circuit adopted in the present embodiment 1 or 2, and adopts the circuit protection method described above in the present embodiment 3;

[0039] Preferably, in this embodiment, the vehicle controller control system 10 includes a high-voltage side power supply HVDC Power and a low-voltage side power supply LVDC Power respectively electrically connected to the IPM module 4, the high-voltage side power supply HVDC Power adopts the DC power supply 13 as described in Example 1 or 2, the EMI power filter 12 serves as the high-voltage side power filter, and the low-voltage side power supply LVDC Power also adopts a DC type power supply; wherein the voltage of the high-voltage side power supply HVDC Power is not less than 100V, and the voltage of the low-voltage side power supply LVDC Power is not higher than 50V;

[0040] For further information, see Figure 5 As shown, preferably, in this embodiment, the voltage +HV of the high-voltage side power supply HVDCPower is 350V, which is connected to the IPM module 4; at the same time, the low-voltage side power supply LVDC Power passes through the low-voltage side EMI power filter 21 and SMPS (abbreviation of Switching Mode Power Supply in English), and outputs +15V low-voltage power to the IPM module 4 through the SMPS; MCU1 inputs IGBT-contorl signal to IGBT15 through the IGBT drive circuit 2a; the drive signal sent by MCU1 to the IPM module 4 specifically includes: 6PWMs, that is, 6-tube PWM drive signal; IPM module 4 outputs U, V, W phase voltage drive signals to the motor 3.

[0041] In order to further illustrate the technical solution of the present application, since the voltage +HV of the high-voltage side power supply HVDC Power is 350V, the following device models and related parameters are specifically selected in this embodiment:

[0042] DC bus capacitor 11: manufacturer is muRata; model is FHA50Y206KS, capacity is 20uF, withstand voltage is 630V;

[0043] EMI power filter 12: includes a common mode inductor CMC and a differential mode inductor DMI, wherein the inductance of the common mode inductor CMC is 1270uH and the rated current is 25A; the inductance of the differential mode inductor DMI is 3.3uH and the rated current is 26A;

[0044] Integrated package of diode 14 and IGBT 15: manufacturer is ROHM, model is RGS00TS65E, rated current is 50A, withstand voltage is: 650V;

[0045] The withstand voltage of the IPM module 4 is: 650V; the preset threshold value = 550V; the interval time = 1s, that is, 1 second.

[0046] It should be noted that this application specification Figure 4Other structural solutions disclosed in the invention belong to the well-known structural solutions in the field of vehicle-mounted compressor control and are not the innovative contents of the present application, so they will not be described one by one.

[0047] In other embodiments, when the voltage +HV of the high-voltage side power supply HVDC Power is 750V, the preset threshold can be set at 900V, and two DC bus capacitor units connected in series are equipped. The withstand voltage of a single bus capacitor unit is 630V, so the withstand voltage of the DC bus capacitor unit reaches 1260V; and an IPM module with a withstand voltage of 1200V is selected; these are conventional technical choices that can be made by technicians in this field based on the contents recorded in this application, and these are not special limitations of this application.

[0048] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0049] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A vehicle controller control system, characterized in that: The invention comprises a circuit based on a DC bus capacitor, wherein the circuit comprises a DC bus capacitor connected to a motor drive module, the MCU is connected to the motor drive through the motor drive module, and the DC bus capacitor is connected to the DC power supply through a power filter; the vehicle-mounted controller control system comprises a high-voltage side power supply and a low-voltage side power supply respectively electrically connected to the motor drive module, and the high-voltage side power supply adopts the DC power supply; wherein the voltage of the high-voltage side power supply is not less than 100V, and the voltage of the low-voltage side power supply is not higher than 50V; the circuit adopts the following circuit protection method: The circuit includes a DC bus capacitor connected to a motor drive module, the MCU is connected to the motor drive through the motor drive module, and the DC bus capacitor is connected to a DC power supply through a power filter; a diode is connected between the power filter and the positive or negative electrode of the DC bus capacitor, and a switch tube driven by the MCU is reversely connected in parallel between the positive and negative electrodes of the diode; The MCU is connected to the DC bus through a voltage sampling circuit, and is used to detect the voltage of the DC bus capacitor in real time, and compare the voltage of the DC bus capacitor with a preset threshold value, and selectively send a switch tube drive signal to the switch tube based on the comparison and judgment result; The positive electrode of the diode is connected to the power filter, and the negative electrode of the diode is connected to the positive electrode of the DC bus capacitor; or the negative electrode of the diode is connected to the power filter, and the positive electrode of the diode is connected to the negative electrode of the DC bus capacitor; Among them, when the motor is not working, the switch tube is in a closed state; When the motor is working, when the voltage of the DC bus capacitor does not exceed the preset threshold, the switch tube is in a closed state; when it is found that the voltage of the DC bus capacitor exceeds the preset threshold, the switch tube is turned on to release the electric field energy stored in the DC bus capacitor to the DC power supply.

2. The vehicle controller control system according to claim 1, characterized in that: When the switch tube is turned on, the motor drive module is turned off.

3. The vehicle controller control system according to claim 2, characterized in that: After the interval time of opening the switch tube, ensure that the voltage of the DC bus capacitor does not exceed the preset threshold, and close the switch tube; the MCU selects to send a drive signal to the motor drive module according to the motor operation requirements.

4. The vehicle controller control system according to claim 3, characterized in that: The interval time is 0.00001-2.5 seconds.

5. The vehicle controller control system according to claim 1, characterized in that: The preset threshold is greater than the rated voltage of the DC power supply and less than the withstand voltage of the DC bus capacitor and the motor drive module.

6. The vehicle controller control system according to claim 1, characterized in that: The capacity of the DC bus capacitor is 2-100uF; the motor drive module includes an IPM module.

7. The vehicle controller control system according to claim 6, characterized in that: The switch tube adopts an IGBT (15); the MCU (1) is connected to the IGBT (15) via an IGBT drive circuit (2a); and the MCU (1) is connected to a DC bus via a voltage sampling circuit (2b).

8. The vehicle controller control system according to claim 7, characterized in that: The low-voltage side power supply is connected to the SMPS via the low-voltage side EMI power supply filter (21), and outputs the low-voltage power supply to the IPM module (4) via the SMPS; the MCU (1) inputs an IGBT-controll signal to the IGBT (15) via the IGBT drive circuit (2a).

9. The vehicle controller control system according to claim 7, characterized in that: The IGBT (15) and the diode (14) are integrated and packaged into one body.

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